1926, apparently coined by South African Gen. J.C. Smuts (1870-1950) in his book "Holism and Evolution" which treats of evolution as a process of unification of separate parts; from Greek holos "whole" (see safe (adj.)) + -ism.

This character of "wholeness" meets us everywhere and points to something fundamental in the universe. Holism (from [holos] = whole) is the term here coined for this fundamental factor operative towards the creation of wholes in the universe. [Smuts, "Holism and Evolution," p.86]